Dr. Eggman is the arch-nemesis of Sonic the Hedgehog, making an appearance in almost every Sonic game. He always makes up evil plans, only to be thwarted by Sonic, who he holds a grudge against. He first debuted in the same game as Sonic, Sonic the Hedgehog. In the game, he captured animals and used them as slaves, trapping them in his robots and making them go against Sonic. All of them were freed at the end, though, and Eggman was defeated. Eggman also hates anybody who befriends and works with Sonic like Tails, Knuckles, Amy, Blaze, Silver, and even Shadow at times.

In Sonic the Hedgehog, Eggman's video game debut, Eggman successfully transforms the harmless animals of South Island into his robotic slaves. He then creates the ultimate weapon to take Sonic, the hedgehog trying to be a hero, and his Chaos Emeralds. Eggman's first attempt fails. Eggman tries once again to defeat Sonic in Sonic the Hedgehog for the Game Gear only to be thwarted once again by the blue blur. At this point, Eggman is frustrated.